1. Field of the Invention
Exemplary aspects of the present invention generally relate to an image forming apparatus, such as a copier, a facsimile machine, a printer, or a multi-functional system including a combination thereof, and a method of forming an image with the image forming apparatus.
2. Description of the Background Art
Conventionally, there is known an electrophotographic image forming apparatus in which types of recording media or paper can be designated and printing carried out under printing conditions suitable for the designated type of the recording medium or paper. Although advantageous, such an image forming apparatus suffers from a drawback in that the number of types of recording media that can be designated is limited, including for example only a thickness of the recording medium, an OHP sheet, and a type of a label sheet.
In recent years, in order to obtain high imaging quality similar to that obtained with traditional silver halide photography, use of high gloss coated paper is increasing. In order to form an image on the coated paper, there is known an image forming apparatus that is equipped with printing capabilities suitable for the coated paper so that printing can be performed on the coated paper.
Furthermore, in order to select the type of recording medium automatically, there is known an image forming apparatus that detects the degree of smoothness of the recording medium as reflectivity and prints under appropriate printing conditions.
In general, it is preferred that the image have a glossiness that is higher than the glossiness of the recording medium on which the image is fixed. When using such coated paper, in order to adequately fuse the toner that forms the image onto the recording medium so that a smooth toner image is obtained, a temperature of image fixation is raised and/or a time for image fixation is extended.
However, when the type of coated paper varies, high glossiness and a high quality image may not be achievable under given printing conditions. To address this problem, in one related-art image forming apparatus, it is determined whether the coated paper is normal high-gloss coated paper or thermoplastic resin coated paper. Printing conditions are changed in accordance with the result, thereby achieving a high-gloss image without degrading image quality.
It is known that, even under identical printing conditions, the quality of an image also differs between dull coated paper and matte coated paper. The glossiness of an image fixed on matte coated paper is not as great as that of an image fixed on dull coated paper. A surface roughness is also different between dull coated paper and matte coated paper, with distances between adjacent microscopic protrusions on the matte coated paper are greater than on dull coated paper. Therefore, a toner layer too readily conforms to the rough surface of the coated paper. In this case, the image remains rough even after image fixation, so that it is difficult to obtain a high-gloss image.
An additional factor complicating the attainment of consistently smooth, high-quality images is that, in order to achieve such high-quality images, toner particle diameters are getting smaller. Toner particles having a small particle diameter are produced more easily using a pulverization method than a polymerization method. In the pulverization method, a particle diameter distribution of the toner particles is narrower than that of the polymerization method, and the shape of the toner particle can be made substantially spherical. However, such toner particles are deposited on the surface of the recording medium densely, and thus toner layers of uniform height are readily formed. As a result, the roughness of the recording medium remains even after image fixation.